129639217 has 2 divisors, whose sum is σ = 129639218. Its totient is φ = 129639216.

The previous prime is 129639151. The next prime is 129639227. The reversal of 129639217 is 712936921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87441201 + 42198016 = 9351^2 + 6496^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129639217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 129639217.

It is not a weakly prime, because it can be changed into another prime (129639227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64819608 + 64819609.

It is an arithmetic number, because the mean of its divisors is an integer number (64819609).

Almost surely, 2^129639217 is an apocalyptic number.

It is an amenable number.

129639217 is a deficient number, since it is larger than the sum of its proper divisors (1).

129639217 is an equidigital number, since it uses as much as digits as its factorization.

129639217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 40.

The square root of 129639217 is about 11385.9218774766. The cubic root of 129639217 is about 506.1106386302.

The spelling of 129639217 in words is "one hundred twenty-nine million, six hundred thirty-nine thousand, two hundred seventeen".